787 and 747-8 landing separation

[Hartington]

FAA puts 10 miles between 787, trailing planes on landing | Chicago Breaking Business (http://chicagobreakingbusiness.com/2010/10/faa-puts-10-miles-between-787-trailing-planes-on-landing.html)

Accepting this is only a first stab by the powers that be is that a bit draconian?

[Intruder]

They've made similar accommodations for the 757 due to it's "dirty" vortices that are apparently out of proportion to its size. Maybe this is one of the down sides to efficiency...

[Starter Crew]

From the WSJ article (http://online.wsj.com/article/SB10001424052748704631504575532373845280544.html?mod=wsj_sha re_twitter) reporting of the original FAA release:

The Federal Aviation Administration restrictions are interim and many industry officials expect them to be substantially loosened once flight tests are completed. But the decision on extra spacing, communicated to air-traffic controllers last week, raises questions about the extent of operating restrictions the agency may end up imposing on Boeing's 787 Dreamliner and stretched 747-8 jumbo jets.
The interim standards call for all planes, regardless of size, to stay at least 10 miles behind the latest Boeing models during large portions of descents. That's more than twice the distance many planes are now required to fly behind the 747-400, Boeing's largest jet currently in service.
The document announcing interim "separation standards and procedures" calls them "conservative" and indicates "final guidance will become available" after flight-test results have been evaluated. But the document indicates the interim restrictions could remain in effect through October 2011.
The FAA's notice said that studies indicate that wakes generated by 747-8 and 787 models—essentially cones of spinning air spreading out from the tip of each wing—"may be more substantial than those" created by existing wide-body or jumbo jets such as the Boeing 747-400 or Airbus A340.

[TopBunk]

PG

A bit of an over-reaction, I would say! If you read the article it saysThe FAA termed the interim standard “conservative” and said final guidance will be issued after 787 and 747-8 flight tests are completed and flight test data have been evaluated.

[grounded27]

interim requirement

Seems logical until it's footprint is fully understood, I am sure that gap will narrow by the time thiese aircraft are in service with volume to have an impact on most airport operations.

Wonder if intruder's imput on the 75 applies, with the 787 we are talking about a wing that maximizes usage of the air that slips off a rigid wing (757) in vortices. With the 778 it's size and displacement of air not just off the wing is an issue.

The quote was interim, no need to get panties in a knot just yet. Doubt boeing would attempt to market an aircraft that would slow down airport ops to this degree at our largest airlines hubs.

[WHBM]

The FAA's notice said that studies indicate that wakes generated by 747-8 and 787 models—essentially cones of spinning air spreading out from the tip of each wing—"may be more substantial than those" created by existing wide-body or jumbo jets such as the Boeing 747-400 or Airbus A340.Isn't understanding this sort of thing on each type what flight tests and FAA certification is meant to be all about ?

And if the caution is with aircraft under test, before these issues are fully worked out, shouldn't the restriction be a standard procedure for all experimental types of this size, not just attached to a specific type ?

[Starter Crew]

From this evening's Seattle Times...

The Federal Aviation Administration on Tuesday rescinded an order issued just last week that mandated 10 miles of separation for aircraft landing behind either of Boeing's two new jets.
"It was issued prematurely," said FAA spokeswoman Laura Brown. "There were a number of errors."